Process for producing a pitch and tarry substance

ABSTRACT

A process for producing pitch and tar characterizing by introducing the raw oil, whose aromatic content is more than 80 percent, into such heat medium as inert gases such as steam heated up to 1,300* to 2,500* C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.001 to 0.1 seconds at a temperature of 900* to 1,500* C. under a pressure 300 mm./Hg. absolute to 20 kg./cm.2 gauge.

United States Patent Inventors Shimpei Gomi;

Takuji Hosol, both of Tokyo, Japan Appl. No. 869,914 Filed Oct. 27, 1969 Patented Nov. 2, 1971 Assignee Kureha Kagaku Kogyo Kabushiki Kalsha Tokyo, Japan Priority Nov. 6, 1968 Japan 43/80593 PROCESS FOR PRODUCING A PITCH AND TARRY SUBSTANCE [56] References Cited UNITED STATES PATENTS 2,767,233 10/1956 Mullen et a1 208/129 X 2,768,119 10/1956 Nash 208/22 2,992,181 7/1961 Renner 208/22 3,317,622 5/1967 Hoertz et al. 208/22 Primary Examiner-Delbert E. Gantz Assistant Examiner-G. E. Schmitkons Attorney- Larson, Taylor and Hinds ABSTRACT: A process for producing pitch and tar characterizing by introducing the raw oil, whose aromatic content is more than 80 percent, into such heat medium as inert gases such as steam heated up to 1,300 to 2,500 C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.001 to 0.1 seconds at a temperature of 900 to l,500 C. under a pressure 300 mmJHg. absolute to 20 kg./cm.gauge.

PROCESS FOR PRODUCING A PITCH AND TARRY SUBSTANCE This invention relates to a process for producing the pitch or tar suitable for a carbon material or a blending material by heat-treating at a high temperature for a short time hydrocarbons rich in aromatics which are a light fraction of coal tar or byproduct tar produced by thermal cracking of petroleum hydrocarbons.

Pitch or tar has already been used as a binder or a blending material in producing carbon products such as a graphite electrode or carbon brick and tar resin products such as an epoxy tar or a urethane tar. It is required to be high aromaticity from such characteristics of the products as coking value, capability, sintering property and graphitizability for carbon materials. High aromaticity is also expected to give the compatibility with resins and the chemical stabilities to oils and chemicals, as required in tar resins and other similar products. The tar produced by carbonization coal or by thermal cracking of petroleum hydrocarbon in producing gaseous fuels is mostly utilized as such, but such the tar not only has a defect containing ash in itself, but is also limited in the range of operation conditions because it is a byproduct. That is to say, it is mostly difl'lcult to expect controlled quality. Sometimes modifications of those tar are reformed by distillation or heat treatment at about 600 C. Yet, no tar having satisfactory properties has been always obtained to date. As seen in the graphite electrode industry, for example, the remarkably advanced industrial technique of electric arc furnaces in steel industry and electrolytic cells various industries recently requires electrodes of higher performances. Even in the case of tar resins, the expansion of their uses and the improvement of their products can not be coped, in respect of both quality and quantity, with the conventional tar or pitch products made by the simple distillation or heat treatment of the byproduct tar or pitch.

A main object of the present invention is to directly produce and provide the pitch or tar satisfying the above-mentioned performances.

The process of the present invention shall be explained in detail as follows.

' it is characterized by introducing such the raw oil rich in aromatic hydrocarbons as, the light oil (such as the washing oil or anthracene oil) from the byproduct of the carbonization of coal or the light oil fraction from the bottom oil byproduced by the thermal cracking of such petroleum hydrocarbon as naphthas, gas oils or other light distilliates for the purpose of producing gaseous fuels and or olefins such as ethylene, propylene and butadiene into such heat medium as inert gases including steam heated up to l,300-2,500 C. or complete combustion flame of the same temperature range made by fuel and air or oxygen, and by allowing it to react for a short time of about 0.00] to 0.l seconds at a comparatively high reaction temperature of 900 to 1,500 C. under a pressure of about 300 mm. Hg. absolute to kg./cm. gauge, so that the aliphatic hydrocarbons in the raw oil may be thermally cracked and the dealkylation and condensation of the aromatic hydrocarbon may be caused and, as a result, these tar and pitch consisting of such aromatic hydrocarbons having very few side chains and high thermal stability may be produced. The degree of condensation can be adjusted so as to realize the best performances of the product by controlling such treating conditions as the temperature, pressure and time. The tar and pitch thus produced by high temperature thermally cracking are high in aromaticity and thermally stable and besides they are comparatively uniform in the size of the condensed aromatic rings which are connected with alkylene and they have a comparatively narrow molecular weight distribution. It is therefore comparatively well-controlled in the molecular weight and molecular structure and has resinous property. Therefore, when it is used as raw material for carbon products, it will show such surprising performances as a high coking value, high-cakeing and sintering properties and high graphitizability. Further, as a blending material for tar resins, it will show such very excellent performances that it is high in the compatibility with the resins and is high in the resistance against water, oils and chemicals. It is clear that the tar or pitch produced by the present invention is very excellent to the conventional products produced under very ambiguous producing conditions, since these are byproducts. In short, the process of the present invention is to provide the resinous pitch or tar and may be said to suggest a process for producing cheap industrial tar resins which will be seriously required in the near future.

The temperature range of the heat medium to be used in the process of the present invention is preferably 1,300 to 2,500 C. If the heat medium temperature is higher than 2,500" C., the temperature difference from the reaction temperature will be so large that the reaction will become not only nonuniform but also, in case the heat medium is steam or combustion flame, radicals produced by its dissociation will promote the nonuniformity of the reaction, thereby producing an overreacting part and unreacting part. Particularly the former will give carbon black and the result will not be desirable. Further, if the heat medium temperature is lower than l,300 C., the temperature difference from the reaction temperature will be so small that much energy will be consumed in vain and the result will be uneconomical. The aromatic content of the raw oil hydrocarbons is more than percent and the HIC atomic ratio is less than 1.2, or preferably more than percent and less than 1.1 respectively. If these conditions are not satisfied, the gasification rate by the thermal cracking will be so high that not only much energy will be wasted but also the yield of products will be low. The treating temperature range is 900 to l,500 C. or preferably l,000 to l,300 C. If it is lower than 900 C., the conversion rate will be low. If it is higher than l,500 C., the quality control of tar and pitch becomes difficult and it will not be desirable.

The treating pressure is 300 mm. Hg. absolute to 20 kg./cm. gauge or preferably the atmospheric pressure to 10 kg./cm. gauge. If it is lower than 300 mm. Hg. absolute, the reaction rate will be low. If it is higher than 20 kg./cm. gauge, not only the power cost will increase but also a coke deposit in the reactor will be resulted by the condensation of the produced pitch or tar and it will not be desirable. Further, the treating time is in the range of 0.001 to 0.1 seconds or preferably 0.003 to 0.05 seconds. If it is less than 0.001 seconds, the conversion will be low. Further, if it is more than 0.1 seconds, the produced pitch or tar will lose the features of the present invention, and it will not be desirable.

The process of the present invention shall be explained in the following examples.

EXAMPLE 1 Fifteen Nm. /hr. of propane were burned by using 35 NmF/hr. of air, in a combustion chamber of 20mm. inside diameter by 200mm. length lined with a refractory material. A

washing oil having the properties shown in table lwas introduced at a rate of 20 kg./hr. into the obtained high-temperature gas stream of about l,750 C., and is allowed to react for 0.008 sec. under a pressure of 3 kgJcm gauge at the reaction temperature of about l,l50 C. The products obtained is shown in table 2.

Among the products, the heavy fraction (pitch) of a boiling point above 400 C. under the atmospheric pressure had the properties shown in table 3 and was high-(about 30 percent higher than the conventional products) coking value and graphite electrode in which it was used as a binder showed the following results. It was about 5 percent higher in the apparent specific gravity, about 25 percent higher in the electric conductivity and about 35 percent higher in the compressive strength (sinteravility) than those of the conventional products Raw oil Properties:

hydrocarbon: l by weight. More than 98% by eight.

H/C atomic ratio: 0.96

3.3% by weight.

4.7% by weight. 30.3% by weight. 22.8% by weight.

38.6% by weight. 0.3% by weight.

Table 3: Pitch properties:

Softening point: 95.320 C. "K: atomic ratio: 0.56 Benzene insoluble: Quinoline insoluble: Volatile matter: Fixed carbon:

Ash content:

38% by weight by weight 42% by weight 58% by weight Less than 0.1% by weight lBP represents the initial boiling point EP represents the end point EXAMPLE 2 With the same apparatus as in Example 1, a tar obtained by thermally cracking a light petroleum hydrocarbon to produce unsaturated hydrocarbon such as ethylene, propylene and butadiene and having the properties shown in table 4 was introduced at a rate of 30 kg./hr. into a high-temperature gas steam produced by the combustion of the same amount of propane and air as in the example 1, and was allowed to react at a temperature of about l ,080 C. under a pressure of 5 kg./cm. gauge. The products obtained are shown in table 5.

The heavy fraction (tar) thus formed of a boiling point above 250 C. under the atmospheric pressure had the properties shown in table 6 and was very high in the compatibility with an epoxy resin in which it was used as a blending material. it contained low acidic components, sulfur and ash contents, and therefore when it was mixed with a resin and a curing agent, it gave such high stability that it stood long preservation, and the resin products obtained from it showed excel lent resistance against water, oils and chemicals.

Further, when this tar was used as a urethane tar, it proved to be not only suitable for two-component type urethanes but also applicable to one-component urethanes.

Table 4: Raw all properties:

(ethylene cracker bottom oil) lBP: 230 C. 5?: 350 C. Naphthalene content: Sulfur content: Aromatic hydrocarbon: H/C atomic ratio:

5.8% by weight 0.02% by weight More than 96% by weight 0.98

Table 5: Product yields:

Gas (CO. H,, CH C,H,.

CIHI): 4.% by weight Prefraction (at IE? to ZlB C. 4.0% by weight Naphthalene: |5.2% by weight Intermediate fraction: 25.3% by weight (at 218' to 250 C.

Tar (above 250 C.): 50.9% by weight Ash content: Less than O.I% by weight Less than 9.05% by weight Sulfur content:

EXAMPLE 3 mm. length lined with refractory materials, a tar used in exampie 2 was introduced at a rate of 27 kg./hr. into a 60 kg./hr.

stream of steam of about l,700 C. produced by a regenerative heating system-two regenerative furnaces were switch heated to conduct the combustion and the steam heating alternately-and was allowed to react for 0.002 seconds at a temperature of about l,220 C. under the atmospheric pressure to give the product of the results shown in table 7 The heavy fraction of a boiling point above 480 C. under the atmospheric pressure had the properties shown in table 8, showed a high coking value and high graphitizability and was very excellent as a raw material for carbon and graphite materials of high-coking and sintering property.

Table 7:

Gas(CO. H,, CH C,H,.

C,H.): i by weight Prefraction (at lBP to 2l8 C.) 4.8% by weight Naphthalene: 13.3% by weight Intermediate fraction: 44.0% by weight (at 218 to 480 C.) Heavy fraction (pitch):

(above 480 C.)

32.2% by weight Loss: 2.7% by weight Table 8:

Softening point: 195 C.

l-l/C ratio: 0.52

97.5% by weight 48.0! by weight Trace 24.0% by weight n-C, insoluble part: Benzene insoluble part: Oulnoline insoluble part: Volatile matter:

1. A process for producing pitch and tar characterizing by introducing the raw oil, whose aromatic content is more than percent, into such heat medium as inert gases such as steam heated up to l,300 to 2,500 C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.001 to 0.1 seconds at a temperature of 900 to l,500 C. under a pressure 300 mm. Hg. absolute to 20 kgJcm gauge.

2. A process for producing pitch and tar suitable for a carbon material or for a blending material to tar resins characterizing by introducing the raw oil, whose aromatic content is more than 80 percent. into such heat medium as inert gases such as steam heated up to 1,300 to 2,500 C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.001 to 0.1 seconds at a temperature of 900 to l.500 C. under a pressure 300 mm. Hg. absolute to 20 ltgJcm gauge.

3. A process for producing pitch and tar suitable for a car bon material or for a blending material to tar resins characterizing by introducing the raw oil, whose aromatic content is more than 80 percent and whose H/C atomic ratio is less than 1.2, into such heat medium as inert gases such as steam heated up to l,300 to 2,500 C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.00l to 0.1 seconds at a temperature of 900 to l,500 C. under a pressure 300 mm. Hg. absolute to 20 kgJcm gauge.

t i t i t 

2. A process for producing pitch and tar suitable for a carbon material or for a blending material to tar resins characterizing by introducing the raw oIl, whose aromatic content is more than 80 percent, into such heat medium as inert gases such as steam heated up to 1,300* to 2,500* C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.001 to 0.1 seconds at a temperature of 900* to 1,500* C. under a pressure 300 mm. Hg. absolute to 20 kg./cm2 gauge.
 3. A process for producing pitch and tar suitable for a carbon material or for a blending material to tar resins characterizing by introducing the raw oil, whose aromatic content is more than 80 percent and whose H/C atomic ratio is less than 1.2, into such heat medium as inert gases such as steam heated up to 1,300* to 2,500 C. or complete combustion flame of the same temperature range produced by using fuel and air or oxygen, thus allowing it to react for 0.001 to 0.1 seconds at a temperature of 900* to 1, 500* C. under a pressure 300 mm. Hg. absolute to 20 kg./cm2 gauge. 